Apparatus for separating gas from a fibre suspension

ABSTRACT

In an apparatus for separating gas from a high consistency fibre suspension, the apparatus comprising a rotor chamber (2) containing a first rotor (11) provided with blades (10), a gas space (3) containing a second rotor (13) provided with blades (12), a wall disposed between the rotor chamber and the gas space consititutes an annular gas discharge channel surrounding a shaft rotating the rotors. Rotating blades (14) are disposed in the gas discharge channel between the first and the second rotor.

The present invention relates to an apparatus for separating gas from afibre suspension. The apparatus is particularly intended to be used forpulps of high consistensy, e.g. 6 to 15%. An apparatus of this kind forseparating gas is disclosed e.g. by U.S. Pat. No. 4,410,337.

An object of the present invention is to provide an apparatus by which adisadvantage of the apparatus of the above U.S. patent can beeliminated.

The air contained in the pulp is removed through a discharge channel ina wall between a rotor chamber and a gas space. In order to prevent pulpfrom flowing into the gas space during operation the annular gasdischarge channel must be as low as possible. Consequently the channelis easily clogged. The channel can be maintained open by the solutionprovided by the present invention which is substantially characterizedby the feature that rotating blades are disposed in the gas dischargechannel between a first and a second rotor. Preferably the gas dischargechannel expands in the direction of flow so as to facilitate thedischarge of pulp from the channel.

The invention is described in detail below with reference to theaccompanying drawing in which

FIG. 1 is a sectional view in the length direction of an embodiment ofthe apparatgus according to the invention.

FIG. 2 is sectional view along line A--A of FIG. 1.

The apparatus illustrated in the figures comprises a housing 1containing a rotor chamber 2 and a gas chamber or space 3. Between therotor chamber and the gas space, a wall 4 is disposed to form a gasdischarge channel 5 around a shaft 6 which is rotatably mounted onbearings, said channel connecting the rotor chamber and the gas space toeach other. The housing is provided with an inlet 7 through which pulpis supplied into the rotor chamber, and an outlet 8. The gas space isprovided with an outlet 9. A rotor 11 provided with blades 10 (firstblades) is mounted on the shaft in the rotor chamber. Another rotor 13provided with blades 12 (second blades) is mounted on the shaft in thegas space. Blades or ribs 14 (third blades) rotated by the shaft aredisposed in the gas discharge channel between the first rotor 11 and thesecond rotor 13. Blades 10, 14 and 12 constitute a surface extendingfrom the first rotor to the other. The outer surface 15 of the gasdischarge channel is provided with grooves 16. The shaft is driven by adevice which is not illustrated on the drawing.

While rotating, the rotor 11 sets the pulp in an inlet channel 17 inrotating motion whereby air and pulp are separated from each other andan air bubble surrounded by pulp is formed in the center of the rotor.The rotor also fluidizes the pulp which enables transport of highconsistency pulps.

The air separated from the pulp is guided from the rotor chamber intothe gas space via outlets 19 in a back wall 18 of the rotor 11 and viathe gas discharge channel and is removed through the outlet 9.

While rotating, the ribs 14 (third blades) functioning as extensions ofthe first blades 10 of the rotor 11 cause the pulp which may haveentrained in the channel to flow and thus keep the channel open. Groovesor recesses 16 intensify the effect of the ribs.

The blades of the rotor 13 prevent the gas space from being clogged andfluidize the pulp gathered in the gas space during a stand-still.

The invention is not limited to the embodiment illustrated as anexample, only, but it can be modified within the scope of protectiondefined by the patent claims.

We claim:
 1. Apparatus for separating a gas from a high consistencyfiber suspension comprising:a housing including an inlet and outlet forhigh consistency fiber suspension; a rotor chamber in said housingcontaining a first rotor portion provided with first blades; a gaschamber in said housing containing a second rotor portion provided withsecond blades; a shaft operatively connected to the rotor portions foreffecting rotation of the rotor portions about a common axis ofrotation; a wall between the rotor chamber and the gas chamber definingan annular gas discharge channel surrounding said shaft; and thirdblades disposed in said gas channel between said first and second rotorportions, and operatively connected to said shaft for rotation therewithwherein said inlet is located above said rotor chamber, and said outletis located in a peripheral surface of said rotor chamber.
 2. Anapparatus as recited in claim 1, characterized in that the outer surfaceof the gas discharge channel is provided with grooves.
 3. An apparatusas recited in claim 1, characterized in that at least a part of thethird blades constitute a surface extending from one rotor portion tothe other.
 4. Apparatus as recited in claim 3 wherein the gas dischargechannel expands towards the gas chamber.
 5. Apparatus as recited inclaim 3 wherein the outer surface of the gas discharge channel isprovided with grooves.
 6. An apparatus as recited in claim 1,characterized in that the gas discharge channel expands towards the gaschamber.
 7. Apparatus as recited in claim 6 wherein the outer surface ofthe gas discharge channel is provided with grooves.